Effect of IL-1beta, TNF-alpha and IL-4 on complement regulatory protein mRNA expression in human articular chondrocytes.

Most of the cells possess complement regulatory proteins (CRPs) that protect them against complement-mediated damage. In our previous work we revealed that human articular chondrocytes express CPRs. Moreover, increase of CRPs expression after treatment of chondrocytes with proinflammatory cytokines IL-1beta and TNF-alpha has been demonstrated by ELISA technique. Chondroprotective cytokine IL-4 stimulated expression of CD46 only. In this work RT-PCR technique was used to evaluate the expression of mRNA of cell surface CPRs in cultured isolated articular human chondrocytes after treatment with IL-1beta, TNF-alpha and IL-4. Chondrocytes stimulated with IL-1beta and TNF-alpha showed augmented levels of CD46, CD55 and CD59 mRNA. Treatment with IL-4, however, increased only the level of CD46 mRNA. These results confirm and extend our previous observations. CD35 mRNA was not found. Expression of complement regulatory proteins on chondrocytes and its upregulation by cytokines stimulating matrix degradation could be important for the protection of these cells against complement-mediated lysis, which might be caused by immunocomplexes deposited in articular cartilage in inflammatory joint diseases.